Electric safety-fuse.



C. N. SACHS. ELECTRIC SAFETY FUSE. APPLICATION FILED J'AN.16, 1905.

1,016,524, Patented Een. 6, '1912.

Witnesses: i In'z/G/UT:

7*" CV. Ji. Racks,

UNITED STATESv PATENT oEEioE.

CARCLINE N. sACHs-or HAaTCnD, CONNECTICUT, Assioma To THE sACHs ComrANY,or HARTFORD, CONNECTICUT, a CoaroEarIoN or CCNNECTIGUT.-

Specification of Letters Patent.

Batenteu Feb. e, 1912.

Application led January 16, 1905. Serial No 241.169,. y

To all whom t may 4concern Be it known that I, CAROLINE N. SAoHs,

. a citizen of the United States, and resident of Hartford, in thecounty of Hartford and State of Connecticut, have invented certain newand useful Improvements 1n Electric Safety-Fuses, of which the followingis a full, clear, and exact specification.-

This invention relates to an improved safety fuse used to protectelectric circuits.

, which melts 'at a comparatively low temperature. It is the commonpractice to inclose this fuse strip in a casing or tube which is filledwith a loose powdered or granulated material of an insulating charactersurrounding th'e fuse and held about it by the casing. Upon the ruptureof the fuse by an excessive current, the loose material surrounding thevfuse absorbs the metallic vapor resulting from the rupture, thusbreaking up the arc and dissipating the heat energy by reducing thetemperature .of the expanding gases. The rapidity with which thisabsorption takes place depends largely upon the area of the surface ofcontact bef tween the fuse and the surrounding material. For this reasonthe fuse conductor is commonly made in the form of a at strip. The widthof the strip cannot, however, be very largely'increased Without undulyincreasing the diameter of the casing and in other ways creatingtroublesome conditions.

It is the object of the present invention to provide a safety fuse stripin which the metal is so distributed as to be in contact with acomparatively large amount of filling material, while'at the sametimebeing of such a form as-to enable it to be inclosed within amoderate sized casing and making the proper terminal connections.

In carrying out this invention, it is preferable to employ l'a thinsheet of zinc or other suitable metal, the thickness depending upon thecapacity of the fuse. This thin sheet of metal is cut in a band thewidth of which is the same as the desired length of the finished fusestrip. It is then either rolled,

lfolded or otherwise longitudinally bent in such a manner that the foldsor convolutions of the strip are separated froml each other suiicientlyto allow the space between the portions to be filled withinsulatingmaterial. The ends of the bentor rolled strip.Y

are then connected by solder or other con'- tinuous or integral metallicconnection to suitable terminals by which the fuse may be connected tothe exterior or circuit wires.

The' embodiments of the invention are herein shown in connection with a`type of fuse adapted to be placed in a suitable clip or holder, the'circuit wires being attached either to the holder or directly to theterminals of the fuse.

Figure 1 of the drawin s is a side view in" section through thelongitudinal center, of one form of fuse where ,the circuit wires areintended to be attached to the holder. Fig.

2 is anv end view of the fuse in section through the line 2-2 of Fig. 1.Figs. 3 and 4 are sectional side and end views corresponding to Figs. 1and 2 showing a modified form of the fuse. Figs. 5 and 6 are sectionalside' and end views respectively of lstill another modifiedconstructionof the fuse. Figs. 7, 8 and 9 are views of the inner ends ofthe terminals shown in 1, 3

'and 5, respectively.

. In Eig. 1 the metal band 12. has been rolled into a spiral form withasbestos fabric 13 between the convolutions. 'The metal at the a ends ofthe fuse strip thus formed extends beyond the asbestos cloth and issoldered into the terminal cups 14. To thus connect the.strip to theterminals it is preferable to first flow molten solder into the cup andthen to immerse the strip ends in this solder which after hardeningmakes a permanent connection between the terminal and the metal of thefuse strip proper. The cups 14 are connected to the `terminals 20, WhicheX7 tend through the ferrules 1.9 on the ends of the casing 18. Thespace within the casing between the fuse strip and the inner surface ofthe casing is filled with powdered o r granular insulating material 21.Upon the rupture of the metal strip 13 by an excessive current, thegases resulting therefrom are absorbed and dissipated through theasbestos strip 13 and the surrounding granular material 21. i

In Figs. 3 and 4 the metal and the asbestos cloth are rolled into a formwhich mightbe called a fiat sided spiral, the metal convolutions 26being separated by the asbestos cloth vfolds oi: the tuse strip is a 27.Holes 30 are drilled through the metal in order to permit the fuse torupture more easily at that portion of the fuse than elsewhere. Theterminals 28 are provided with saw cuts 29 into which are soldered theprojecting ends of the metal strip, the llat sides of the lspiralpermitting the edges of the metal to properly fit the saw-cuts. rlhefuse is surrounded withfilling 3l contained within a ,casing 32. i 4

Figs. 5 and 6 show another modified form of the fuse strip. In this casethe band of asbestos cloth 35 is made somewhat-longer than the band ofmetal,l so that its convolu-` tions continue beyond the end of the metalband 34, thus enabling it to form a covering for both the metal and theasbestos adjacent thereto. The metal may then be secured by solder 37 tothe terminal cups 36 from which extend terminals 38 to which the currentcarrying wires may be cdnnected. This forin -may be employed without anyexterior casing if the end of the asbestos band is secured so that itcannot unroll. lt is preferable, however, to employ a casing l0 similarto that shown in the other figures.`

rlhe carrying capacity of theuse may be varied by correspondinglyvarying the width of the metal. rlhe extended area of surface alif'ordedby this form of fuse strip is olE special utility in connection withlarge fuses, since it gives a large area of contact with the fillingmaterial and hence disperses more gases resulting from the rupture ofthe fuse, thereby also quenching more promptly the yarc attendant uponthe rupture. In cases where asbestos or similar fabric is employed forenveloping the strip the comparatively loose weave of the fabric affordsnumerous interstices for the dispersion of the heat and gases. j

While the use of the intervening layer ci asbestos 'cloth between theconvelutions or simple-way of obtaining the desired result, the spacebetween the convolutions, bends or folds may be filled in any ner. "Forinstance, a felt insulating wrap ping may be used, made of asbestoslibere loosely associated to form a felted cloth and this cloth may beused in the same' manner as the woven cloth. Or the space may be filledwith any suitable powdered, granu# lated or otherwise iinely dividedmaterial, such for instance as the loose material used tosurround theexterior of fhe strip in the :lorns of Figs. l and in this case, thestrip `may be rolled up spirally, using any convenient lexible materialas a core, for separating the convolutions, and this core may b'eafterward withdrawn and replaced by the loose material. ln doing this,however, it is advisable to rst solder one end ot the spiral to itsterminal, andthen place aroundfit a retaining 'tube of widely the heatand ordinary 'orconve'nient manone or two I Jfolded, or plicated,

wrappings oi" asbestos paper. Nzitter this the core may be removed andthe granular material substituted for it. l

rlhe terminals are connected to the ends of the roll, or of the folds asthe case may' be so that the current has a direct flow lengthwise of theroll, and substantially at right angles to the direction in which thestrip is folded or rolled. Thus the fuse strip forms a comparative shortbut thin, wide, and continuous conductor through which the current lows.widely dispersed, but undivided. ln order to dispose this widesheet-like conductor compactly as te its transverse or lateraldimensions is rolled or folded together in sinuous convolutions,'asherein described.

Although `the band of sheet metal of which the fuse strip is formed is`preferably rolled into' a spiralform, it may be bent into other formswithout departing from the spirit of this invention. The band may-loebent back andorth upon itself or it may be bent in various other sinuousforms which will give a suitably compact cross-section 1`rVhere a\ looseinsulating material is to be used to separate the different portions ofthe strip, one bent form is about as easily adapted to the, requirementsas another. The spirally-bent form is, however, preferred as it is moreeasily manufactured. andperinits the use of a continuous piece/otinsulating fabric for separating the adjacent portions oft the strip..

lt is generally advisable in fuses of' this class to provide for havingthe rupture take placeat approximately the middle of the length of thefuse strip, in ordercto give" room lengthwise in both directions for theabsorption of the gases by the insulating material. For this purpose thestrips herein shown the portion where it is desired to have thecross-section maybe accomplished in Various ways; as for example, byrolling the sheet metal' a little thinner at this portion oi its length,or holes like that shown at 3G in F ig. 3 may be made in the metaleither before or after ,the band is bent linto its iinal form. Theseperforations 30 afford `a simple and inexpensive way ofreducing thecross sectional area of the fuse strip so as to predetermine thelocation of the rupture.

Also when using iinely divided insulating material between the folds orconvolutions, these perforations enable the powdered insulation .to passthrough the band at these central portions and thus aid in thedistribution of the insulating material..

The term bent is herein employed to may be formed in various ways toprovide a reduced areaof cross-section at4 designate broadly any rolledor sinuses form in which the sheet may be doubled, or

or rolled, 'or otherwise bent, so as to dispose` the sheet-like form inclose lateral compass with a space Abetween the folds, or plications,for insulating materials. 'The terminals are attached to the. ends oflthe rolled or folded fuse, considering it in its completed form, and thecurrent flows longitudinally of the roll or fold, in the sense that itflows in a longitudinal di: rection through the folded structure,parallel with the lines upon which the sheet is folded or rolled, orotherwise bent, instead of flowing in a transverse direction to andfollowing the sinuosity or bends of the structure.

I claim as my invention y 1. The combination in electrical fuses, of

a fuse strip consisting of a band of metal disposed in a roll havinginsulating ma-v terial between its convolutions, and connecting members4fused to, and between the convolutions of the opposite ends of the rollfor connecting it to circuit terminals.

A cut-out for electric circuits, comprising a sheet of thin metaldisposed in superposed layers separated by insulating material, andmeans soldered to and betweenthe ends of said layers for connecting thesaid ends of the sheet in circuit.

3. The combination in electrical fuses, of a fuse strip consisting of aband of metal disposed in a roll having insulating Inaterial between theconvolutions, conducting members joined by fusion to and between theconvolutions of the opposite ends of the roll, and a casing inclosi'ngthe fuse and connected to the said members for connection with circuitterminals.

4. A fuse strip consisting of a rolled band of metal, terminals solderedto the ends and between the convolutions of the roll to carry the.current longitudinally of the roll, the said roll having an area ofcross section which is smaller at a4 point between the ends of the rollthan at the said ends.

5. A fuse comprising a sheet of metal and a sheet of insulating materialforming a roll with the insulating material separating the plies of themetal sheet, terminals eX- tending from the ends of the metal roll andjoined to andbetween the plies thereof by fusion, and nely dividedinsulating ma.-

terial surrounding the roll. 6.' In an electric fuse, the combination ofsuperposed layers of sheet insulation, a sheet metal fusible lmemberinterposed between of said fusible member.

' .7. In an electric fuse, the combination of a roll of sheetinsulation, a sheet of fusible met-al lextending therethrough andprojecting beyond the ends lof said roll, and metallic connectionssoldered to the projecting lends of the metal sheet.

8. In an electric fuse, the combination of a roll of sheet insulation, asheet of fusible metal interposed between tl Y convolutions of ,saidinsulation and projec ing beyond the ends thereof, and metal connectionssoldered to the projecting ends of said metal sheet.

9. In an electric fuse, the-'combination of superposed layers of sheetinsulation, a sheet of metal with a central section of reduced crosssection nterpo'sed between said layers and projecting beyond the endsthereof, and metallic connections soldered to and between the projectingends of said metal sheet.

10. In an lelectric fuse, the combination of a roll of sheet insulation,a sheet of fusible metal interposed between the convolutions of saidinsulation and projectingbeyond the ends thereof,.and metal diskssoldered to the projecting ends of said metal sheet.-

11. A thermal cut out comprising a sheet of thin metal rolled uptransversely with insulation between the several convolutions, 'andsoldered connection extending between the plies at the ends of said rollof metal for connecting it in circuit.

In testimony whereof I have'signed my name to this specification in theCAROLINE N. sAcHs.

Witnesses:

-AILEEN MALONE, WM. H. HoNIss.

Copies of this patent may be obtained for 'five cents each, byaddressing the Commissioner of Patents,A

Washington, D. C.

presence of ltwo subscribing witnesses. i

